SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c529fd03571d3064effe3c63e51892b534a2bb113a4089818fed5c64f17fbe7e' 
  AND token = 'i9ONSSLUVLa8j+zIdvAGq5I5w3fJFyC2sJ1/LPFiScs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}